Injection molding machines are used to produce plastic parts and some versions include hot runners with hot tip or valve gated nozzles. In hot runners having hot tip nozzles, the melt flow is controlled by controlling the heat and/or pressure at the nozzle tip, as is well known. In hot runners having a valve gated nozzle, a valve stem may be used to start and stop melt flow into the mold cavity by reciprocally moving the valve stem into open and closed positions, respectively. An actuator drives the valve stem between the open and closed positions.